The present invention relates to a housing for a gas generator and particularly to a housing for a gas generator used in a pyrotechnic pretensioner for a vehicle safety restraint system.
Such pretensioners are detonated in the event of rapid deceleration of a vehicle, indicative of a crash, and operate to tighten a safety belt around an occupant of the vehicle to more securely restrain the occupant against inertial movement and also to correctly position the occupant for effective deployment of an air bag. The belt is tightened either at the retractor end or at the buckle end so as to take up slack in the system which may be caused by thick clothing worn by the occupant or by the occupant being out of position. Typically 150-180 mm of slack in the belt is taken up by a pretensioner.
Typically a pyrotechnic pretensioner uses a gas generator, detonated when a crash situation is detected, to release pressurised gas to drive a piston along a tube. The piston may be connected by a cable or other such mechanism to a belt buckle fastening point, eg the so-called buckle stalk to pull back the buckle end of the belt. Alternatively it may be connected to the belt retractor to rewind the retractor spool. A clutch connection is typically used here.
In either case the pretensioner generally comprises an elongate cylindrical tube and is typically a rather large and unwieldy item, somewhat difficult to conceal in a vehicle. Traditionally it is mounted under a vehicle seat. The gas generator may be fitted in a separate housing connected to the pretensioner tube pneumatically but a more compact and efficient system is produced if the gas generator housing is integral with the tube, for example mounted coaxially herewith.
For safety reasons it is preferable to fit the actual gas generator as a last operation when the pretensioner is already installed in the vehicle so as to minimise dangers from premature or accidental detonation of the device. In known pretensioners it is difficult to do this while guaranteeing a good seal between the housing and the generator. Also some disassembly of the system, for example of the bracket holding the buckle head is necessary and this is time consuming and hence costly.
The present invention provides a housing for a gas generator comprising a hollow container for supporting a gas generator, the container having a opening for insertion of the gas generator and a tapered end section for cooperating with a gas outlet end of the gas generator to provide a seal around the gas outlet and a cover for closing the container opening, the cover having a tapered wedge portion extending into the container in use to urge the gas generator towards the tapered end of the container.
Preferably the wedge member is integral with the cover for the housing and extends generally perpendicularly thereto.
In a preferred embodiment the cover is provided with extensions overlapping the housing which extensions have means for locking the cover onto the housing.
The locking means may comprise apertures corresponding to apertures on the housing through which roll pins can be inserted to hold the cover to the housing.